Method of and apparatus for twisting together a plurality of elongated flexible elements

ABSTRACT

A PLURALITY OF WIRES OR OTHER ELONGATED FLEXIBLE ELEMENTS TAKEN FROM STATIONARY SUPPLY DEVICES ARE ASSEMBLED TO FORM A BUNCH. THE BUNCH IS ADVANCED AND ROTATED BY A STATIONARY DRAWING DEVICE, WHICH MAY BE A SKEW ROLL OR AN ENDLESS BELT, HAVING AN ENDLESS GRIPPING SURFACE WHICH MOVES IN A CLOSED PATH AND ENGAGES THE BUNCH OVER A PART OF THAT CLOSED PATH WHICH IS OBLIQUENTLY INCLINED WITH RESPECT TO THE AXIS OF THE BUNCH. THE ROTATING BUNCH IS TAKEN UP BY A DOUBLE-TWIST BUNCHING MACHNE WHOSE FLYER ROTATES IN THE SAME DIRECTION AS THE BUNCH BUT AS A LOWER SPEED

Nov. 16, 1971 H. H. DAKER ETAL 3,620,001

METHOD OF AND APPARATUS FOR TWISTING TOGETHER A PLURALITY 0F ELONGATEDFLEXIBLE ELEMENTS Filed May 26, L969 5 Sheets-Sheet 1 B 41/ MW RAM"- 1lllomey:

Nov. 16, 1971 H. H. DAKER l-rrAL 3,620,001

METHOD OF AND APPARATUS FOR TWISTING TOGETHER A PLURALITY 0F ELONGATEDFLEXIBLE ELEMENTS Filed May 26, L969 3 Sheets-Sheet 2 Nov. 16, 1971 H.H. DAKER ETAL 3,620,001

METHOD OF AND APPARATUS FOR TWISTING TOGETHER A PLURALITY OF ELONGATEDFLEXIBLE ELEMENTS Filed May- 26. 1969 S Sheets-Sheet 5 In color Aims;wfiiszz r 306w Peri 91 (AX/A ltorney) United States Patent 3,620,001METHOD OF AND APPARATUS FOR TWISTING TOGETHER A PLURALITY OF ELONGATEDFLEXIBLE ELEMENTS Horace Herbert Daker, Sidmouth, Devon, Raymond AlfredMartin, Lancashire, and John Rose, Cheshire, England, assignors toBritish Insulated Callenders Cables Limited, London, England Filed May26, 1969, Ser. No. 834,930 Claims priority, application Great Britain,May 28, 1968, 25,535/ 68 Int. Cl. D01h 1/10 US. Cl. 5758.57 17 ClaimsABSTRACT OF THE DISCLOSURE A plurality of wires or other elongatedflexible elements taken from stationary supply devices are assembled toform a bunch. The bunch is advanced and rotated by a stationary drawingdevice, which may be a skew roll or an endless belt, having an endlessgripping surface which moves in a closed path and engages the bunch overa part of that closed path which is obliquely inclined with respect tothe axis of the bunch. The rotating bunch is taken up by a double-twistbunching machine whose flyer rotates in the same direction as the bunchbut at a lower speed.

This invention relates to a method of and apparatus for twistingtogether a plurality of elongated flexible elements by means of a doubletwist bunching machine. With such machines the flexible elongatedelements to be twisted together are drawn off from storage devices(which may be a group of bins or stationary reels or a group of reels ofwhich each reel is mounted for rotation about its axis on a stationarystand) and led into the bunching machine which essentially comprises atake-up device, usually a rotatably driven reel, and a flyer which isrotatably driven about the take-up device and conveys the bunch ofelongated flexible elements first forwards axially of the machine andthen in a loop rotating around the take-up device (which normallyremains stationary in space) and then axially rearwards toward thetake-up device. Such machines impart a twist of 720 to the bunchedelongated flexible elements during each complete revolution of the flyerof the bunching machine relative to the take-up device, one half of thistwist being put in at the entry end of the flyer and the other half atthe delivery end of the flyer.

Machines of this kind are relatively cheap as compared with tubularstanding or laying-up machines in which the supply reels are mounted ina rotating tube or tubes or in a tubular frame or frames and the twistedtogether elongated flexible elements are drawn off from a closing die'by a capstan or other form of haul-01f located at the front end of thetube or frame and thence fed to a takeup reel. Double twist bunchingmachines are capable of producing technically satisfactory bunched andtwisted elongated flexible elements in many cases but diflrculties areencountered in attempting to produce on such machines heavy =fine wirestrand, that is to say strand formed of a very large number of finewires, for example over two hundred wires. This difliculty arises fromthe fact that in a given length of strand the length of the individualwires will vary according to the position they occupy in the strand.With tubular stranders and single twist bunching machines there is nodifficulty as the wires are automatically drawn oif their respectivesupply devices at correspondingly slightly different rates. In the caseof a double twist bunching machine this is possible only with respect tothe first twisting stage. Between that stage and Patented Nov. 16, 1971the second twisting stage the wires are locked together and twisting inthe second stage can only result in the stretching of the outer wires ofthe strand or in an excess length of wire in the inner wires of thestrand. The former is obviously undesirable; the latter can result insurplus wire being forced outwards from the interior of the strand.

Difliculties are also encountered in attempting to layup together on adouble twist bunching machine two or more insulated conductors togetherwith fillers in the form of cotton rovings or other elongated elementsof low tensile strength used to impart a substantially circularcross-section to the cable before proceeding to apply a tubular braidto, or to extrude a sheath on, the laid-up cores. These are usuallymanifested by breakage of some of the filler elements.

In copending application Ser. No. 714,479 of Sidney R. Santer, filedMar. 20, 1968, now US. Pat. No. 3,504,487, and assigned to B. & F.Carter & Company Limited, there is described a method of twistingtogether a plurality of elongated flexible elements which comprisesdrawing such elements from stationary supply devices, bringing themtogether and forming them into a twisted bunch by drawing means rotatingabout a rectilinear axis within the longitudinally advancing bunch andthen feeding the rotating bunch thus formed into a double twist bunchingmachine whose flyer is driven in the same direction as but at a speedless than the speed of rotation of the longitudinally advancing bunch tothe extent that at least a substanial proportion of, but notsubsantially more than, the twist present in the finished product takenup in the bunching machine is put in prior to its entry into thebunching machine, i.e. at a stage where the difference in length ofcomponents ofthe twisted bunch are compensated for by the differingrates of draw-ofi? from their supply devices. If the speed of rotationof the flyer is half that of the bunch at entry into the bunchingmachine when the take-up is stationary in space, the sole effect of thedouble twist bunching machine is first to take out half the twist in therotating bunch being fed ino it and then to put back the twist which ithas taken out. In the aforesaid specification it is indicated that thedrawing means for forming the elongated flexible elements into a twistedbunch is preferably an endless belt type of hauloff which is bodilydriven in rotation about an axis coincident with or approximating to thelongitudinal axis of advance of the group of elements engaged by it,and/or the axis of the bunching machine associated with it.

The method in accordance with the present invention comprises drawing aplurality of elongated flexible elements from stationary supply devices,assembling them to form a bunch and advancing and twisting the bunch soformed by stationary drawing means having at least one endless grippingsurface which moves in a closed path, the said gripping surface engagingthe bunch over a part of the closed path which is obliquely inclinedwith respect to the axis of the bunch and the bunch is fed into a doubletwist bunching machine whose flyer is driven in the same direction asbut at a speed less than the speed of rotation of the longitudinallyadvancing bunch to the extent that at least a substantial proportion of,but not substantially more than, the twist present in the finishedproduct taken-up in the bunching machine is put in prior to the entry ofthe bunch into the bunching machine.

By stationary drawings means is meant drawing means having no overallmotion which contributes to its advancing and twisting the bunch; minormotion, for example to allow for irregularities in the movement of thebunch, is not excluded.

The endless gripping surface may be the circumferential surface of adriven skew roll, but preferably it is a surface of a driven endlessbelt. (By driven, we mean driven other than by engagement with thebunch.) When askew roll is used, it will normally be necessary to use atleast one, and preferably more than one, backing roll, which should beskewed at the same angle as the driven roll and may or may not bedriven. When an endless belt is used, a backing belt may be used in asimilar manner, or alternatively a single belt may be formed into one ormore helical turns around and in contact with the bunch. A furtherpossibility is to use a driven roll back by a belt or a driven beltbacked by a roll or rolls.

The invention will be more fully described, by way of example, withreference to the accompanying diagrammatic drawings wherein:

FIG. 1 is a general view of apparatus in accordance with the invention,

FIGS. 2 and 3 show one form of drawing means for use in performing theinvention; and

FIGS. 4 and 5 show two further forms of drawing means.

As shown in FIG. 1 a plurality of wires or other elements 1 are takenfrom any convenient source 2 and after passing through appropriatelyarranged apertures in a guide plate 3 are brought together in a closingdie 4. The resulting bunch 5 passes through a drawing device 6 whichserves both to draw it forward and to twist it about its own axis. Fromthe drawing device, the twisted bunch passes via a guide 7 to thedouble-twist bunching machine 8. The twisted bunch 5 now passes aroundthe fiyer 9, which may for example be of the kind comprising alightweight metal how 10 carrying spaced guides 11 and is taken up on areel 12 which is held against rotation about the machine axis and isdriven about its own axis by gearing of a conventional kind, which hasbeen omitted from the drawing in the interest of clarity. The flyer 9 isdriven from a main motor 13 through a layshaft 14 and suitable gears orbelts.

The lfirst drawing device to be described is shown in FIGS. 2 and 3,FIG. 3 being a cross-section on the line [[III-II in FIG. 2, andcomprises a skew roll 15 which is driven for example by a motor 16, in adirection to feed the bunch 5 towards the double-twist bunching machineand to twist it with a left-hand lay. Alternatively, a right-hand laycan be obtained by skewing the roll 15 in the opposite direction. Twobacking rolls 17 are provided to improve the grip of roll 15 and toavoid applying bending forces to the bunch. Rolls 17 are skewed at thesame angle as roll 15, and are preferably also driven, for example bymotors 18.

The peripheral surface of the driven roll or rolls should preferably beelastically yieldable so as to ensure contact between it and the bunchover an appreciable area. The skew rolls may be of rubber or rubber-likematerial or they may be of metal with tyres of such material. The speedof rotation imparted to the bunch and also the linear speed of travelimparted to the bunch will depend upon the peripheral speed of thedriven roll or rolls and upon the skew angle, that is to say upon theangle between the axis of the bunch and the axis of the driving roll.The former will vary from a maximum (with the axis of the driving rollparallel to the axis of the bunch) to zero (with the axis of the drivingroll at right angles to the axis of the bunch), whilst the linear speedof travel of the bunch will vary from zero to a maximum-assuming thatthe skew rolls are permitted to govern the linear speed of travelthrough the double twist bunching machine. By providing for controlledadjustment of the skew of the rolls the pitch of the twist which theyimpart to the bunch before entry into the machine can be adjusted to anydesired value within limits.

FIG. 4 shows a second form of drawing device comprising a single endlessdriven belt 19 which makes one (or more than one) helical turn aroundand in contact with the bunch 5. Guide means 20 are provided as close aspossible to the point where the belt runs on to the bunch, andadditional guide means 21 as close as possible to its point of departurefrom the bunch, to control the angle of the helix, and hence therelationship between the rotary speed of the bunch and its linear speed.By making the lead-on and lead-off belt guides adjustable relative toone another in the direction of the length of the bunch and adjustablein an angular direction relative to the axis of the bunch the pitch ofthe helical turns of the belt about the bunch and hence the pitch of thetwist imparted to the bunch may be varied Within limits. Each belt guidemay comprise a pair of rolls 22, 23, one on each face of the belt, oneor both of these rolls having circumferential ribs 24 lying one to eachside of the belt, and means for imparting angular and/or linear movementto the roll housing relative to the axis of the bunch upon which thebelt operates. One or both of the rolls constituting the belt guide onthe departure side of the bunch may be power driven for example by amotor 25 to impart a drive to the belt. Alternatively a separate drivingpulley may be used. By providing a jockey pulley 26 or other device tomaintain tension in the belt, this drawing device is rendered readilyadaptable to bunches of various diameters. The arrangement shown in thedrawing requires the use of an endless belt 19 having one twist for eachhelical turn about the bunch, but this can be avoided by guiding thebelt through a second helix having the same number of turns of oppositehand.

A third form of drawing device is shown in FIG. 5 and comprises twoendless belts, which for ease of identification will be referred to asthe upper belt 27 and the lower belt 28, inclined at the same angle withrespect to the axis of the bunch. The lower run of the upper belt andthe upper run of the lower belt are slightly spaced from one another,and the bunch 5 passes between and in contact with both of them, the twocontact areas being substantially opposite to one another, so that thetwo belts back each other. Pressure pads 29, 30 engaging respectivelythe upper face of the lower run of the upper belt 27 and the lower faceof the upper run of the lower belt 28 may be used to ensure a highcontact area between the belts and the bunch; if required, these may beprovided with small rolls or belts to reduce friction. At least one, andpreferably each, of the belts 27, 28 is driven so that its bunchengagingrun moves in the direction indicated by the arrow 31 thereon. If bothare driven they will of course be driven at the same linear speed. Oneof many possible drive arrangements is shown and comprises a first bevelgear 32 which is positively driven, preferably through appropriategearing from the main drive for the doubletwist bunching machine, anddrives two further bevel gears 33, which are coupled to the rolls 34, 35supporting the belts 27, 28 by chain-and-sprocket mechanisms 36, 37respectively.

The arrangement shown in FIG. 5 has the advantage over that shown inFIG. 4 that the bending forces applied to the bunch are much smaller,and it avoids the limitation on the belt width set in the FIG. 4apparatus set by the onset of interference between adjacent turns of thehelix. It is also somewhat easier to adjust the lay angle, e.g. bybodily rotation of each of the belts about the axis of bevel gear 32.

In general, the optimum speed of rotation of the bunched elements fed tothe double twist bunching machine by the drawing device is twice that ofthe fiyer of the bunching machine if the bunching machine take-up isstationary in space, as in such a case all the twist present in thefinished product taken up in the bunching machine is imparted prior toits entry into the machine i.e. at a point where it is possible to caterfor the slight additional length of elements required for the radiallyouter part of the bunch as compared with the length of elements requiredfor the central part of the bunch. In the present method the hunch ispreferably driven in rotation at a speed substantially equal to twicethe speed of the fiyer of the bunching machine but satisfactory productsare obtainable by driving the bunch at speeds somewhat less than twicethe speed of the flyer, again assuming the bunching machine take-up isstationary in space. If the speed of the bunch is very substantiallyless than that of twice the speed of the flyer, the twist imparted tothe bunched elements by the skew rolls or endless belt may beinsuflicient to prevent stretching and possible rupture of the outerelements or a surplus length of elements in the m ddle of the bunch mayoccur at the second stage of twisting in the bunching machine. If on theother hand the speed of the bunch substantially exceeds twice the speedof the flyer too much twist may be imparted to the bunched elements bythe skew rolls or the endless belt and the twist that will be taken outat the flyer entry may then result in slack outer elements which willnot be completely taken up by the twist imparted at the flyer delivery.It will be appreciated that the optimum speed of rotation of the skewrolls or speed of the endless belt and hence the optimum speed ofrotation of the bunched elements being fed to the bunching machine canbe raised (with an increase in the throughput speed of the product) ifthe bunching machine take-up is rotated in a direction to add to thetwist put in at the delivery end of the flyer e.g. where the take-updevice is a reel, by rotating the reel bodily about the machine axis ina direction counter to the direction of rotation of the flyer.

As all the components of the bunch drawing and twisting device will havevery much smaller radius of gyration and hence a higher permissiblespeed of rotation than that of the flyer of the bunching machine, whichmust be in excess of the radius of the take-up reel, it is possible notonly to obtain by our invention a technically satisfactory twisted bunchof elongated flexible elements that cannot be produced on a double twistbunching machine alone, but to obtain it at twice or more than tw ce theoutput speed at which it would be obtamable by existing methods on asingle twist bunching machine of the same maximum flyer speed ofrotation.

What we claim as our invention is:

1. A method of twisting together a plurality of elongated flexibleelements, comprising the steps of (a) assembling the elements as theyare withdrawn from stationary supply devices to form a bunch;

(b) advancing and twisting the bunch so formed by stationary drawingmeans having at least one endless gripping surface which moves in aclosed path that is fixed with respect to rotation around the axis ofthe bunch and engages the bunch over a part of the closed path which isobliquely inclined with respect to the axis of the bunch; and

(c) feeding the bunch into a double-twist bunching machine comprisingtake-up means and a flyer rotatable around the take-up means, anddriving the flyer in the same direction as but at a speed less than thespeed rotation of the longitudinally advancing bunch to the extent thatat least a substantial proportion of, but not substantially more than,the twist present in the finished product taken up in the bunch ingmachine is put in prior to the entry of the bunch into the bunchingmachine.

2. A method as claimed in claim 1 wherein the step of advancing andtwisting the bunch is carried out by engaging the bunch with thecircumferential surface of at least one driven skew roll which rotatesabout an axis obliquely inclined with respect to the axis of the bunchand is fixed with respect to rotation around the axis.

3. A method as claimed in claim 2 comprising holding the bunch inengagement with the said driven skew roll by means of at least onebacking roll which is rotatable about an axis that is inclined at thesame angle as the axis of the driven skew roll with respect to the axisof the bunch and is fixed with respect to rotation around that axis.

4. A method as claimed in claim 3 comprising driving the backing roll.

5. A method as claimed in claim 1 in which the step of advancing andtwisting the bunch is carried out by engaging the bunch with at leastone driven endless belt having a path that is fixed with respect torotation around the axis of the bunch over a part of the path of thebelt which is obliquely inclined with respect to the axis of the bunch.

6. A method as claimed in claim 1 in which the step of advancing andtwisting the hunch is carried out by engaging the bunch with a pair ofendless belts each having a path that is fixed with respect to rotationaround the axis of the bunch and the two belts having respectivesurfaces which engage the bunch over parts of their respective pathswhich are equally obliquely inclined with respect to the axis of thebunch and over parts of the bunch which are substantially opposite toone another, so that each of the belts backs the other, and driving bothbelts at substantially the same longitudinal speed.

7. A method as claimed in claim 1 in which the step of advancing andtwisting the hunch is carried out by engaging the bunch with an endlessbelt which makes at least one helical turn around and in contact withthe bunch and is driven in a :path that is fixed with respect torotation around the axis of the bunch.

8. A method as claimed in claim 1, comprising maintaining the take-up ofthe bunching machine stationary and rotating the flyer at a speedsubstantially equal to onehalf of the angular speed imparted to thebunch by the drawing device.

9. Apparatus for twisting together a plurality of elongated flexibleelements withdrawn from stationary supply devices, comprising (a) meansfor assembling the elements to form a bunch;

(b) for advancing and twisting the bunch so formed, stationary drawingmeans having at least one endless gripping surface which moves in aclosed path that is fixed with respect to rotation-around the axis ofthe bunch and means for guiding the bunch in engagement with the saidgripping surface over a part of its closed path which is obliquelyinclined with respect to the axis of the bunch;

(c) a double-twist bunching machine comprising takeup means and a flyerrotatable about the take-up means for receiving the twisted bunch, and

(d) means for driving the flyer of the bunching machine in the samedirection as but at a speed less than the speed of rotation of thelongitudinally advancing bunch to the extent that at least substantialproportion of, but not substantially more than, the twist present in thefinished product taken up in the bunching machine is put in prior to theentry of the bunch into the bunching machine.

10. Apparatus as claimed in claim 9 in which the said stationary drivingmeans comprises at least one skew roll mounted for rotation about anaxis that is fixed with respect to rotation around the axis of the bunchand means for rotating the skew roll.

11. Apparatus as claim in claim 10 in which the peripheral surface ofthe or each driven roll is elastically yieldable.

12. Apparatus as claimed in claim 10, comprising at least one backingroll which is skewed at the same angle as the said skew roll, the axisof the backing roll being fixed with respect to rotation around the axisof the bunch.

13. Apparatus as claimed in claim 12, comprising means for driving thebacking roll.

14. Apparatus as claimed in claim 9 in which the said stationary drawingmeans comprises at least one endless belt which is driven in a path thatis fixed with respect to rotation around the bunch axis and is arrangedto engage the bunch over a part of its path which is obliquely in clinedwith respect to the axis of the bunch.

15. Apparatus as claimed in claim 14 in which the stationary drawingmeans further Comprises a second endless belt and means for driving thesecond belt at substantially the same longitudinal speed as the first inanother path that is fixed with respect to rotation about the axis ofthe bunch, the two belts being arranged to be equally obliquely inclinedwith respect to the axis of the bunch and to engage the bunch over partsthereof which are substantially opposite to one another, so that each ofthe belts backs the other.

16. Apparatus as claimed in claim 9 in which the said stationary drawingmeans comprises at least one endless belt, guides which are fixed withrespect to rotation about the axis of the bunch for forming the beltinto a helix of References Cited UNITED STATES PATENTS 5/1966 Reichelt5777.4 X 4/1970 Santer 5712 JOHN PETRAKES, Primary Examiner US. Cl. X.R.

at least one turn around and in contact with the bunch, 15 57 58 59 5865 and means for driving the endless belt.

